Blastocyst genotyping for quality control of mouse mutant archive: an ethical and economical approach. Transgenic Research. 2015 24 (5): 921-927

Abstract With the advent of modern developmental biology and molecular genetics, the scientific commu- nity has generated thousands of newly genetically altered strains of laboratory mice with the aim of elucidating gene function. To this end, a large group of Institutions which form the International Mouse Pheno- typing Consortium is generating and phenotyping a knockout mouse strain for each of the *20,000 protein- coding genes using the mutant ES cell resource produced by the International Knockout Mouse Con- sortium. These strains are made available to the research community via public repositories, mostly as cryopreserved sperm or embryos. To ensure the quality of this frozen resource there is a requirement that for each strain the frozen sperm/embryos are proven able to produce viable mutant progeny, before the live animal resource is removed from cages. Given the current requirement to generate live pups to demonstrate their mutant genotype, this quality control check necessitates the use and generation of many animals and requires considerable time, cage space, technical and economic resources. Here, we describe a simple and efficient method of genotyping pre-implantation stage blasto- cysts with significant ethical and economic advantages especially beneficial for current and future large-scale mouse mutagenesis projects.